Shaun Thompson at The DIS managed to check out an actual MagicBand and talk to the cast members about them, and found out lot more details on the MagicBands themselves, including color choices, etc.

Some of the more interesting points:

Colors: Red, Blue, Green, Pink, Yellow, Orange, Iconic Gray

From 10 days prior to check-in, any time after you book your reservation, you will be able to choose your colors and either receive them at the resort or have them sent to you (no word if there is an additional charge, but it seems likely).

From 9-5 days, you can still choose a color but you can only pick them up at the resort.

Within 5 days, you cannot choose the color and will only receive “Iconic Gray”

They can be personalized with a name on the inside of the band (9-10 characters) to help distinguish whose is whose (in case people want the same color, no word on if that will cost extra, or if it can be done within the 5 days)

The battery for the active transmitter is good for 2-3 years. After that it won’t function for features that require it and the whole band needs to be replaced.

What isn’t known yet is whether there will be decorations to place on the bands, or “designer” bands available for an upcharge. And I like how Disney refers to gray as “Iconic Gray” to make it sound spiffy…but it’s just gray.

Don’t go looking for these online yet though…they are not yet available to guests.